Rocksthe earth's natural bones

Rocks are the solid mineral materials forming parts in the surface of the earth that are found in the exposed surface or underground or in the oceans. Their are many types of rocks, these include sedimentary, igneous and igneous. All found in different parts of the earth.

Sedimentary rocks are rocks that are formed by the deposition and cementation of materials in the earth and within bodies of water. These types of rocks are formed by the accumulation of sediments.

The three types of sedimentary rocks include clastic, a basic sedimentary rock, clasts are little pieces of broken up rock which have piled up and and have been formed by compaction and cementation, chemical, which are formed by precipitation of minerals in water, and organic, sedimentary debris caused by organic processes, these rocks often contain fossils, the remains of dead living organisms.

sandstone: an example of a clastic sedimentary rock

rock gypsum: an example of a chemical sedimentary rock

limestone: an example of a organic sedimentary rock

Sedimentary rocks are usually found covering covering most of the earths surface. These rocks are formed from the deposition of mud and sand that is buried and compressed to form a solid rock.

On the rock cycle, sedimentary rocks are formed when an igneous rock weathers down, goes through erosion an is deposited, the sediments compact and cement and turn into sedimentary rocks.

Metamorphic rocks are rocks that form from already existing rocks by extreme heat and/or pressure.

Metamorphic rocks have two types, foliated and non-foliated. Foliated rocks include gneiss, shale and schist. Non-foliated rocks include marble, hornfels and quartzite.

foliated rock: gneiss

non foliated rock: marble

Metamorphic rocks are formed by pressures deep in the earth.

Metamorphic rocks can form from both sedimentary rocks and igneous rocks through heat and pressure

Igneous rocks are a type of rock that form through the cooling and solidification of magma or lava.

The types of igneous rocks include Intrusive rocks, which are found underground, and extrusive rocks, which are found above ground.

obsidian: an example of a extrusive igneous rock

diorite: an example of an intrusive igneous rock

Igneous rocks form in areas where volcanic activity is or has been present.

The tools that geologists use to identify rocks include, scratching the rock on a piece of glass to see how soft or hard it is, to make sure it has cleavage or fracture, to find what color it is by streaking it on a piece of porcelain, and to find its composition.

rock scratch test

here, the rock is being scratched on a piece of glass to test out the hardness.

acid on rock test

here, drops of acid are put onto the rock to test out if it will fizz or not.

rock streak test

here, the rock is being streaked on a piece of porcelain to see what other colors it is.

rock/mineral composition chart

Rocks are made up of minerals, which are defined by geologists as naturally occurring inorganic solids that have a crystalline structure and a distinct chemical composition.